1. Field of the Invention
The present general inventive concept relates to a developing cartridge and an image forming apparatus including the same, and more particularly, to a developing cartridge having a plurality of developers having different printing characteristics and an image forming apparatus including the same.
2. Description of the Related Art
In general, an image forming apparatus is provided with a photosensitive body in which an electrostatic latent image is formed, a developing unit which develops developer on the photosensitive body, and a transferring unit which transfers the developer developed on the photosensitive body to a printing medium, which is called an electrophotographic image forming apparatus. The electrophotographic image forming apparatus includes a printer, a photocopier, and a multi-function printer.
FIG. 1 is a schematic view illustrating a configuration of a developing cartridge 20 used for a conventional image forming apparatus 10. The developing cartridge 20 is detachably provided in the image forming apparatus 10. The developing cartridge 20 is consumable to be replaced with a new one if the developer stored inside is used up. The developing cartridge 20 includes an electrifying part 23 which electrifies an image receptor 21 to a predetermined electric potential, the image receptor 21 on a surface of which an electrostatic latent image is formed by exposure of an exposure part (not shown) after it is electrified to the predetermined electric potential through the electrifying part 23, a developer feeding unit 25 which is in contact with the image receptor 21 and spreads the developer on the electrostatic latent image on the surface of the image receptor 21, a supplying part 28 which supplies the developer to the developer feeding unit 25, a developer regulating member 27 which regulates the amount of the developer supplied to the developer feeding unit 25, and a developer storing part 29 in which the developer is stored.
The developing cartridge 20 is traded and distributed independently from the image forming apparatus 10. Here, the developing cartridge 20 goes through various environment experiments not to generate a storage problem on the way of distribution after it is produced. That is, a storage condition inside the developing cartridge 20 is experimented by changing a package condition, humidity, temperature, and so on. Also, a process for adjusting ingredients included in the developer is performed according to the experiment result.
In the conventional developing cartridge 20, a ratio of a high polymer resin forming the developer through the above adjusting process is increased to improve the storage property of the developer stored inside during its distribution. However, in a case that the ratio of the high polymer resin is increased, the durability of the developer improves, but there may be a problem that a fusing quality and brilliance in a color image are deteriorated. Also, there is a problem that the fusing quality is more deteriorated in a case of an image forming apparatus performing a speed-up printing.
Meanwhile, in a case that the ratio of a low polymer resin included in the developer increases so as to improve the fusing quality and the brilliance in the color image, a glass transition temperature of the developer lowers and the developer is deteriorated during its distribution, thereby lowering its storage property.
In addition, in the conventional developing cartridge 20 storing the developer in which the ratio of the low polymer resin has increased, the developer is held in a nip N between the developer regulating member 27 and the developer feeding unit 25 in the distributing process after manufactured, and the developer held in the nip N is deteriorated under a high temperature environment to be attached to a surface of the developer regulating member 27. The developer attached to the developer regulating member 27 can not be restored to its original property to remain on the surface of the developer regulating member 27 even after the developing cartridge 20 is mounted to the image forming apparatus 10.
If the developer regulating member 27 in which the developer is attached is used to form an image, a streak “a” illustrated in FIG. 2, and a migration “b” illustrated in FIG. 3 are generated on the printed image, thereby deteriorating a printing quality.
The streak “a” is generated by an effect of the developer attached to the developer regulating member 27 and is formed in a proceeding direction of a printing medium if an image is formed. Also, the migration “b” is generated by an effect of the developer attached to the developer feeding unit 25 and is formed in a horizontal direction with respect to the proceeding direction of the printing medium in a rotational cycle of the developer feeding unit 25.